Re: Question on random number generator

Linda wrote in message <[EMAIL PROTECTED]>... >I want to generate a series of random variables, X with exponential >PDF with a given mean,MU value. However, I only want X to be in some >specified lower and upper limit?? Say between 0 -> 150 i.e. rejected >anything outside this range Does anyone ha

Re: Question on random number generator

In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] (Linda) wrote: >I want to generate a series of random variables, X with exponential >PDF with a given mean,MU value. However, I only want X to be in some >specified lower and upper limit?? Say between 0 -> 150 i.e. rejected >anything outside this

Re: Which is faster? ziggurat or Monty Python (or maybe something else?)

George Marsaglia wrote in message <0l7b8.42092$[EMAIL PROTECTED]>... > .. chunk deleted > >The Monty Python method is not quite as fast as as the Ziggurat. > >Some may think that Alan Miller's somewhat vague reference to >a source for the ziggurat article suggests disdain. The source is >Journ

Re: Which is faster? ziggurat or Monty Python (or maybe something else?)

Art Kendall <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I tend to be more concerned with the "apparent randomness" of the results than with >the speed of the algorithm. > > As a thought experiment, what is the cumulative time difference in a run using th

Re: can multicollinearity force a correlation?

[ snip, previous problem] > > This is similar to a problem I have come across: the measurement of a > serum value against exposure. > My theory is that they are correlated. But the data says that they > have an R^2 of 0.02 even though the p-value for the beta is p=1E-40 > (ie. zero). > > As y

Re: homogeneity of variance

and will you not, by this approach, wind up making a _lot_ of pairwise comparisions, with all the implications that have recently been disucssed even here at edstat? Messing with weakly formed data rarely strethens it. I love some transformations, but take them for what they are. Jay Thomas

Re: homogeneity of variance

n my book, if they simply happen to have been recorded or measured in the wrong units/ scale -- so they will be fixed by transformation. You probably ought to be re-thinking your whole scientific hypothesis and test, if your problem is worse than that. TS> > If the data are approxima

Re: If T-Test can not be applied

On Thu, 14 Feb 2002 23:48:02 +0100, "Matthias" <[EMAIL PROTECTED]> wrote: > Hello, > > would be nice if someone can give me some advice with regard to the > following problem: > > I would like to compare the means of two independent numerical sets of data > whether they are significantly differ

Re: If T-Test can not be applied

In SPSS output ignore the lines for equal variances, and use the lines for unequal variances. Matthias wrote: > Hello, > > would be nice if someone can give me some advice with regard to the > following problem: > > I would like to compare the means of two independent numerical sets of data > w

Re: Which is faster? ziggurat or Monty Python (or maybe something else?)

I tend to be more concerned with the "apparent randomness" of the results than with the speed of the algorithm. As a thought experiment, what is the cumulative time difference in a run using the fastest vs the slowest algorithm? A whole minute? A second? A fractional second? Glen wrote: > "A

Re: If T-Test can not be applied

Excuse the bad grammar or typo noted below... It's been a "long morning" already, and it's still not 9 am... :) Bill On Fri, 15 Feb 2002, William B. Ware wrote: > What are your samples sizes? If there are equal or nearly so, the t-test *they* > is robust wit

Re: Which is faster? ziggurat or Monty Python (or maybe something else?)

Marsaglia's ziggurat and MCW1019 generators are available in the R package SuppDists. The gcc compiler was used. George Marsaglia wrote: > > Glen <[EMAIL PROTECTED]> wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > "Alan Miller" <[EMAIL PROTECTED]> wrote in message > news:

Re: If T-Test can not be applied

What are your samples sizes? If there are equal or nearly so, the t-test is robust with regard to unequal variances. On the other hand, you could just read the part of the output that reports results for "equal variances not assumed." You might also consider using a nonparametric procedure such

Re: Which is faster? ziggurat or Monty Python (or maybe something else?)

Glen <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > "Alan Miller" <[EMAIL PROTECTED]> wrote in message news:... > > The fastest way to generate random normals and exponentials is to use George > > Marsaglia's ziggurat algorithm.

Re: Which is faster? ziggurat or Monty Python (or maybe something else?)

Glen wrote in message ... >"Alan Miller" <[EMAIL PROTECTED]> wrote in message news:... >> The fastest way to generate random normals and exponentials is to use George >> Marsaglia's ziggurat algorithm. > >I've seen both ziggurat and Monty Python approaches claimed as

Re: homogeneity of variance

There's a multiple comparison procedure called Games-Howell that is similar to the Aspin-Welch-Satterthwaite statistic in that it has no assumption about variances. -Original Message- From: "Thomas Souers" <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] Date: Thu, 14 Feb 2002 16:47:05 -0800

Re: If T-Test can not be applied

"Matthias" <[EMAIL PROTECTED]> wrote in message news:... > Hello, > > would be nice if someone can give me some advice with regard to the > following problem: > > I would like to compare the means of two independent numerical sets of data > whether they are signifi

Re: If T-Test can not be applied

it's called the behrens-fisher problem ... there is nothing that says that population variances HAVE to be equal essentially what you do is to be a bit more conservative in your degrees of freedom ... most software packages do this as the default ... or at least give you the choice between mak

Re: one-way ANOVA question

On 13 Feb 2002 09:48:41 -0800, [EMAIL PROTECTED] (Dennis Roberts) wrote: > At 09:21 AM 2/13/02 -0600, Mike Granaas wrote: > >On Fri, 8 Feb 2002, Thomas Souers wrote: > > > > > > 2) Secondly, are contrasts used primarily as planned comparisons? If > > so, why? > > > > > > >I would second those wh

Re: Query: pdf of an AR process

In article <[EMAIL PROTECTED]>, Shahram Hosseini <[EMAIL PROTECTED]> wrote: >Hi everybody, >The discrete random process n(t), uniformly distributed in the interval >(-0.5,05), is filtered by a first order AR system to generate the >sequence s(t)=a*s(t-1)+n(t). What is the probability density func

Re: Statistics Tool For Classification/Clustering

Rishabh Gupta <[EMAIL PROTECTED]> wrote in message a4eje9$ip8$[EMAIL PROTECTED]">news:a4eje9$ip8$[EMAIL PROTECTED]... > Hi All, > I'm a research student at the Department Of Electronics, University Of > York, UK. I'm working a project related to music analysis and > classification. ===

Re: Statistics Tool For Classification/Clustering

Hi all, I recieved numerous replies to my query. I can't thanks everyone individually so I want to thank everyone who has replied. I am now looking through the information and links that you have provided. Many Thanks For All Your Help!! Rishabh "Rishabh Gupta" <[EMAIL PROTECTED]> wrote in me

Re: F-test

can you bit a bit more specific here? f tests AND t tests are used for a variety of things give us some context and perhaps we can help at a minimum of course, one is calling for using a test that involves looking at the F distribution for critical values ... the other calls for using a t dis

Re: Statistics Tool For Classification/Clustering

"Richard Wright" <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Genres are presumably groups. So linear combinations of variables that > best separate the genres would be more effectively found by linear > canonical variates analysis (aka discriminant analysis)

Re: Statistics Tool For Classification/Clustering

You might consider a form of PLS - your measurmenets may be highly correlated, and only a very few can do you any good. You have a great many output vars, and few enough inputs. Jay Rishabh Gupta wrote: > Hi All, > I'm a research student at the Department Of Electronics, University Of > Yo

Re: How to generate random numbers from a joint PDF

May be, [ http://www.gloriamundi.org/var/wps.html, Levin, Alex working paper] will help you? Bests, AL "Chia C Chong" <[EMAIL PROTECTED]> wrote in message a4f57c$su1$[EMAIL PROTECTED]">news:a4f57c$su1$[EMAIL PROTECTED]... > Hi! > > I want to generate a set of random numbers from a joint PDF,f(

Re: Statistics Tool For Classification/Clustering

Genres are presumably groups. So linear combinations of variables that best separate the genres would be more effectively found by linear canonical variates analysis (aka discriminant analysis). Richard Wright On Thu, 14 Feb 2002 03:18:48 GMT, "Jim Snow" <[EMAIL PROTECTED]> wrote: snipped >

Re: Statistics Tool For Classification/Clustering

"Rishabh Gupta" <[EMAIL PROTECTED]> wrote in message a4eje9$ip8$[EMAIL PROTECTED]">news:a4eje9$ip8$[EMAIL PROTECTED]... > Hi All, > I'm a research student at the Department Of Electronics, University Of > York, UK. I'm working a project related to music analysis and > classification. I am at

Re: How to generate random numbers from a joint PDF

Chia C Chong wrote in message ... >Hi! > >I want to generate a set of random numbers from a joint PDF,f(A,B) in which >f(A,B)=f(A|B)f(B). f(A|B) is Gaussian PDF in with zero mean,MU and >stdev,SIGMA varies with B according to a Weibull equation and f(B) is an >exponential PDF.How can I do that? >

Re: test differences between proportions

Rich Ulrich wrote: > > On Mon, 11 Feb 2002 13:56:46 +0100, "nikolov" > <[EMAIL PROTECTED]> wrote: > > > hello, > > > > i want to test the difference between two proportions. The problem is that > > some elements of these proportions are dependent (i can not isolate them). > > That is, the t-stat

Re: Statistics Tool For Classification/Clustering

classification is a specialized field go to http://www.pitt.edu/~csna/ and click on although this is the Classification Society of North America members of the British Classification Society also follow it. SPSS should be able to handle what you want to do. However, you need face-to-face consul

Re: Statistics Tool For Classification/Clustering

In sci.stat.math Rishabh Gupta <[EMAIL PROTECTED]> wrote: [ snip ] It seems that you are new to the field of pattern recognition. In that case, you may want to check out the classic book "Pattern Classification" by Duda, Hart and Stork. There is a second edition that came out in 2001. It is a c

Re: Statistics Tool For Classification/Clustering

"Rishabh Gupta" <[EMAIL PROTECTED]> wrote in a4eje9$ip8$[EMAIL PROTECTED]:">news:a4eje9$ip8$[EMAIL PROTECTED]: > Hi All, > I'm a research student at the Department Of Electronics, University > Of > York, UK. I'm working a project related to music analysis and > classification. I am at t

Re: MAD shrimp statistics

"Robert J. MacG. Dawson" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED]... > > > "Wuensch, Karl L" wrote: > > > > How about simply using the M.A.D.? No, not the mad spouse who noticed she > > was getting short-shrimped, rather the mean absolute deviation of individual > > shrimp fro

Re: Book/textbook on applied math with expectation/variance

Thank you. I will search for it. max --- "kjetil halvorsen" <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > A book which seems to comply with your requirements are > P Whittle's "Probability based on expectation", in its 4.th edition from > Springer. Kjeti

Re: one-way ANOVA question

At 09:21 AM 2/13/02 -0600, Mike Granaas wrote: >On Fri, 8 Feb 2002, Thomas Souers wrote: > > > > 2) Secondly, are contrasts used primarily as planned comparisons? If > so, why? > > > >I would second those who've already indicated that planned comparisons are >superior in answering theoretical que

Re: one-way ANOVA question

Thomas Souers wrote: > > Hello, I have two questions regarding multiple comparison tests for a one-way ANOVA >(fixed effects model). > > 1) Consider the "Protected LSD test," where we first use the F statistic to test the >hypothesis of equality of factor level means. Here we have a type I err

Re: one-way ANOVA question

On Fri, 8 Feb 2002, Thomas Souers wrote: > > 2) Secondly, are contrasts used primarily as planned comparisons? If so, why? > I would second those who've already indicated that planned comparisons are superior in answering theoretical questions and add a couple of comments: 1) an omnibus test

Re: Book/textbook on applied math with expectation/variance

A book which seems to comply with your requirements are P Whittle's "Probability based on expectation", in its 4.th edition from Springer. Kjetil Halvorsen maximus wrote: > > Thank you. I will look for the book and others with advanced level of > difficulty. > > max > > - > > "Rich Ulric

Re: Ansari-Bradley dispersion test.

Hola! For a more robust test, which not assumes equal centers, use the fligner-Killeen test. Kjetil Halvorsen Glen Barnett wrote: > > Rich Ulrich <[EMAIL PROTECTED]> wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > On Sat, 09 Feb 2002 16:59:34 GMT, Johannes Fichtinger > > <[

Re: Well I'll be damn!!!!

[EMAIL PROTECTED] wrote: > > WHY WAIT FOR THE SUNDAY PAPER? > > Huh...and here I though the poster managed to get him/herself excommunicated! = Instructions for joining and leaving this list, remarks about the problem of INAPPROPR

Re: can multicollinearity force a correlation?

> low-fat vegan diet" would be close). However, the incidence of heterozygous > familal hypercholesterolemia is only 1:500,000, so this exposure contributes > little to the variance in serum cholesterol in the population; its r^2 would > be small. > > -Jay Thanks, This is similar to a problem

Re: Infinitely divisibility of Generalized Gamma distribution

In article , Alex Levin <[EMAIL PROTECTED]> wrote: >Hi all, >Does anybody know if a Generalized Gamma (GG) distribution is infinitely >divisible for ALL power parameters Nu: -inf(GG r.v. is a Nu-s power of a Gamma distributed r.v. G(Alpha,Beta): >GG(Nu,Alpha,Beta)=

Re: 'Distance' between two normal distributions

Is there any optimality or other reason for the choice of the two below distances? There are surely many other possibilities (e.g. Mallow's distance), which, however, might not be as appropriate, but at the moment I do not see any reasoning. Could you please comment/advise on this? TIA Robert N

Re: test differences between proportions

nikolov <[EMAIL PROTECTED]> wrote: > i want to test the difference between two proportions. The problem is that > some elements of these proportions are dependent (i can not isolate them). > That is, the t-statistics does not work. How could i do? Do other kind of > tests exist? Is there a book o

Re: RE :

J. Random Loser in Dnepropetrowsk wrote: > > The "Listsoft & Co" company offers save your money. > We prepositionals the softwere. Ah. That really fills me with confidence. The are : > > 1. MS WINDOWS 2000 PROFESSIONAL + (SERVICE PACK 2)- 1C

Re: Preparation for PhD in Statistics

Herman Rubin wrote: > > > I would tend to reject any book which does data analysis; > I consider cookbook statistics to be putting a loaded gun > in the hands of an someone who is totally ignorant about > guns; not necessarily an idiot, as the idiot cannot learn. > For data analysis, change "gu

Re: Book/textbook on applied math with expectation/variance

Thank you. I will look for the book and others with advanced level of difficulty. max - "Rich Ulrich" <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > On Sat, 9 Feb 2002 01:17:14 +0900, "maximus" <[EMAIL PROTECTED]> wrote: > > > It may seem odd with the qu

Re: Ansari-Bradley dispersion test.

Rich Ulrich <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > On Sat, 09 Feb 2002 16:59:34 GMT, Johannes Fichtinger > <[EMAIL PROTECTED]> wrote: > > > Dear NG! > > I have been searching for a description of the Ansari-Bradley dispersion test up to now for > > ana

RE :

The "Listsoft & Co" company offers save your money. We prepositionals the softwere. The are : 1. MS WINDOWS 2000 PROFESSIONAL + (SERVICE PACK 2)- 1CD -$15 2. MS WINDOWS 2000 SERVER + (SERVICE PACK 2)- 1CD -$15 3. MS WINDOWS 98 SE 1CD -$13 4. MS WINDOWS MIL

Re: Book/textbook on applied math with expectation/variance

On Sat, 9 Feb 2002 01:17:14 +0900, "maximus" <[EMAIL PROTECTED]> wrote: > It may seem odd with the question in the title, but I want to read and have > some more > practice with (applied) math with expectation/variance, which is in many > forms, for example > with max/min, integration (inside or

Re: Ansari-Bradley dispersion test.

On Sat, 09 Feb 2002 16:59:34 GMT, Johannes Fichtinger <[EMAIL PROTECTED]> wrote: > Dear NG! > I have been searching for a description of the Ansari-Bradley dispersion test up to >now for > analysing a psychological research. I am searching for a description of this test, >specially a > descrip

Re: Preparation for PhD in Statistics

It would be very imporatnt to get a good background in logic and epistemology. A wide liberal arts background that taught critical thinking in general would be invaluable. In order to put statistics in perspective, a good self-teaching effort would be to scan the abstracts for the Joint Statist

Re: Preparation for PhD in Statistics

In article , Michael Hochster <[EMAIL PROTECTED]> wrote: >Here are my thoughts on this. The most important mathematical >requirements are calculus, real analysis, and linear algebra. >You need to to know these topics thoroughly. Whatever >textbooks are used for under

Re: Preparation for PhD in Statistics

Here are my thoughts on this. The most important mathematical requirements are calculus, real analysis, and linear algebra. You need to to know these topics thoroughly. Whatever textbooks are used for undergraduate math majors wherever you are are probably fine. You also need to know non-measure t

Re: can multicollinearity force a correlation?

Wuzzy <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > And that sounds impossible. I suspect a programming error. > > > > -Jay > > you're right i programmed a food database incorrectly but i've redone > it and yep the correlation was only 0.20 for kcal or so.

Re: can multicollinearity force a correlation?

picture.. Much like "golden standard" method of deattenuation.. It didn't work. it is interesting to re-assign food frequencies to people by using that whichi is predicted by 24hr.. anyway it was fun to try..

Re: can multicollinearity force a correlation?

> And that sounds impossible. I suspect a programming error. > > -Jay you're right i programmed a food database incorrectly but i've redone it and yep the correlation was only 0.20 for kcal or so. it is hard to program a database *into* another database easy to make errors.. i've made many err

Re: Preparation for PhD in Statistics

First of all thank you for all replying to my original question. Out of curiousity, at what textbook level should one's understanding of analysis, linear algebra, statistics, probability, etc be upon entering a a typical PhD program. I am trying to gauge which gaps in my background I need to fil

Re: can multicollinearity force a correlation?

Wuzzy <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi Rich, okay i'll post the reason why I ask: > > It is because I am validating a 24hr dietary recall questionnaire > using > a food frequency questionnaire: It doesn't make sense to do that. > Amazingly I

RE: shrimp statistics

Title: Message Well, if this had happened in my house, and my wife observed what I was doing, the statistic to look at would be spousal homicide in North Carolina, 2002.   reg -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Karl L. Wuensch

Re: one-way ANOVA question

Hi On 8 Feb 2002, Thomas Souers wrote: > 2) Secondly, are contrasts used primarily as planned > comparisons? If so, why? There are a great many possible contrasts even with a relatively small number of means. If you examine the data and then decide what contrasts to do, then you have in some i

Re: one-way ANOVA question

At 10:37 AM 2/8/02 -0800, Thomas Souers wrote: >2) Secondly, are contrasts used primarily as planned comparisons? If so, why? well, in the typical rather complex study ... all pairs of possible mean differences (as one example) are NOT equally important to the testing of your theory or notions

Re: one-way ANOVA question

You have to keep in mind that the LSD is concerned with familywise error rate, which is the probability that you will make at least one type I error in your set of conclusions. For the familywise error rate, 3 errors are no worse than 1. Suppose that you have three groups. If the omnibus null is t

Re: can multicollinearity force a correlation?

Hi Rich, okay i'll post the reason why I ask: It is because I am validating a 24hr dietary recall questionnaire using a food frequency questionnaire: as someone else pointed out i got an error, also a perfect correlation for pearsons. it is much more complicated than this but that is the scoo

Re: can multicollinearity force a correlation?

On 5 Feb 2002 18:01:15 -0800, [EMAIL PROTECTED] (Wuzzy) wrote: > > You made a model with the "exact same exposure in different units", > > which is something that no one would do, > > Hehe, translation is don't post messages until you've thought them > through. > > Anyway, turns out that the a

Re: can multicollinearity force a correlation?

In article <[EMAIL PROTECTED]>, Wuzzy <[EMAIL PROTECTED]> wrote: >Is it possible that multicollinearity can force a correlation that >does not exist? >I have a very large sample of n=5,000 >and have found that >disease= exposure + exposure + exposure + exposure R^2=0.45 >where all 4 exposures a

Re: 'Distance' between two normal distributions

In article , Francis Dermot Sweeney <[EMAIL PROTECTED]> wrote: >If I have two normal distributions N(m1, s1) and N(m2, s2), what is a >good measure of the distance between them? I was thinking of something >like a K-S distance like max|phi1-phi2|. I know it probably

Re: EViews 3.1 error message

7;m using 3.1 and it > opens the 4.0 workfile no problem but when I hit the estimate button > (via FIML) it returns: error, near singular matrix. As far as I know > the workfile was unchanged from the one that worked fine in 4.0. Do I > need to create a new workfile in 3.1 and re-enter the equ

Re: Case-cross over

On Thu, 7 Feb 2002 13:20:44 +0100, "Anna Axmon" <[EMAIL PROTECTED]> wrote: > Hi, > > does anyone know if there is a textbook on case-cross over design? > "case crossover design" (in quotes) gets 258 hits reported in google. I did not notice a textbook review, but those should lead you to wh

Re: time series analysis

than some vague references to "an appropriate" method. Can someone > recommend an approachable reference? On careful re-reading, this is not the question that I expected from its first line. Now I gather that the precise lack of uniformity does not bother you for its lack

Re: Sensitivity Analysis

JJ Diamond <[EMAIL PROTECTED]> wrote: : sensitivity analysis is not the same as sensitivity and specificity : from epidemiology. these latter terms are used when describing the : characteristics of a diagnostic test and they ultimately relate to the : utility of a test for diagnosis. my memory s

Re: Sensitivity Analysis

tivity analysis. Further info can be obtained from P Armitage & G > >Berry, "Statistical Methods in Medical Research", Blackwell Scientific > >Publications. Judy Conn > > > > > -Original Message- > > > From: Rich Ulrich [SMTP:[EMAIL PR

Re: 'Distance' between two normal distributions

Francis Dermot Sweeney wrote: = > If I have two normal distributions N(m1, s1) and N(m2, = > s2), what is a good measure of the distance between them? = > I was thinking of something like a K-S distance like = > max|phi1-phi2|. I know it probably depende on what I > want it for, or what

Re: 'Distance' between two normal distributions

seems, as you have said, depends what you want to do with it if there is considerable overlap, then whatever distance you use will have some of both distributions included ... if there is essentially no overlap ... then any pair of values ... one from each ...will reflect a real difference of

RE: Sensitivity Analysis

I think of when talking >sensitivity analysis. Further info can be obtained from P Armitage & G >Berry, "Statistical Methods in Medical Research", Blackwell Scientific >Publications. Judy Conn > > > -Original Message- > > From: Rich Ulrich [SMTP:[E

Re: can multicollinearity force a correlation?

I can't help it. the last paragraph in this post absolutely _demands_ a response. Wuzzy wrote: > > You made a model with the "exact same exposure in different units", > > which is something that no one would do, > > Hehe, translation is don't post messages until you've thought them > through. >

RE: Sensitivity Analysis

t;, Blackwell Scientific Publications. Judy Conn > -Original Message- > From: Rich Ulrich [SMTP:[EMAIL PROTECTED]] > Sent: Wednesday, February 06, 2002 9:55 AM > To: [EMAIL PROTECTED] > Subject: Re: Sensitivity Analysis > > On 31 Jan 2002 10:06:36 -0800, [EMAI

Re: Sensitivity Analysis

On 31 Jan 2002 10:06:36 -0800, [EMAIL PROTECTED] (Christopher J. Mecklin) wrote: > I had a colleague (a biologist) ask me about sensitivity analysis. I am > not familiar with the technique (above and beyond knowing that the > technique exists). What books/articles/websites/etc. would be good s

Re: can multicollinearity force a correlation?

To: [EMAIL PROTECTED] Date sent: 5 Feb 2002 18:15:00 -0800 From: [EMAIL PROTECTED] (Wuzzy) Organization: http://groups.google.com/ Subject: Re: can multicollinearity force a correlation? > In my own defense: > > I

Re: can multicollinearity force a correlation?

In my own defense: I was asking a simple question: will highly correlated cause an irregularly high R^2. My answer to my own question is "no" it can't.. No-one here was able to give me this answer and I believe it is correct: if your sample is large enough,(as mine is) then "no", multicolline

Re: can multicollinearity force a correlation?

> You made a model with the "exact same exposure in different units", > which is something that no one would do, Hehe, translation is don't post messages until you've thought them through. Anyway, turns out that the answer to my question is "No".. Multicollinearity cannot force a correlation.

Re: can multicollinearity force a correlation?

Would you please post the 5 * 5 R matrix? Wuzzy wrote: > Is it possible that multicollinearity can force a correlation that > does not exist? > > I have a very large sample of n=5,000 > and have found that > > disease= exposure + exposure + exposure + exposure R^2=0.45 > > where all 4 exposures

Re: Interpreting mutliple regression Beta is only way?

On 4 Feb 2002 16:14:11 -0800, [EMAIL PROTECTED] (Wuzzy) wrote: > > > > In biostatistical studies, either version of beta is pretty worthless. > > Generally speaking. > > If I may be permitted to infer a reason: > if you have > > bodyweight= -a(drug) - b(exercise) + food > > Then the standar

RE: can multicollinearity force a correlation?

Title: RE: can multicollinearity force a correlation? > Is it possible that multicollinearity can force a correlation that > does not exist? > > I have a very large sample of n=5,000 > and have found that > > disease= exposure + exposure + exposure + exposure R^2=

Re: can multicollinearity force a correlation?

On 5 Feb 2002 08:28:05 -0800, [EMAIL PROTECTED] (Wuzzy) wrote: > Is it possible that multicollinearity can force a correlation that > does not exist? > > I have a very large sample of n=5,000 > and have found that > > disease= exposure + exposure + exposure + exposure R^2=0.45 > > where all 4

Re: Preparation for PhD in Statistics

Cengiz: I'd say pure and applied mathematics by which I mean real analysis, linear algebra and numerical methods. -- Rodney Sparapani Medical College of Wisconsin Sr. Biostatistician Patient Care & Outcomes Research (PCOR) [EMAIL PROTECTED] http://www.mcw.edu/

Re: can multicollinearity force a correlation?

I'm curious to know why you're using the same exact exposure in different units. I've included a dichotomized version of a continuous exposure variable to look at potential threshold effects, but I've never heard of anyone doing what you've described. At 08:28 AM 2/5/02 -0800, Wuzzy wrote: >

Re: factor analysis

In article <[EMAIL PROTECTED]>, Roland Pesch <[EMAIL PROTECTED]> wrote: >HI, >I'm trying to perform factor analysis on mosses from 1028 moss >monitoring sites, each of which was chemically anaylsed on 20 heavy >metal elements. All of these samples do not follow a normal distribution >pattern, th

Re: An Interesting Student Problem

The word "prove" has at least two meanings. One is to test (as in "the proof of the pudding is in the eating"). It is not unreasonable to guess that Darwin might have been using the word in this somewhat archaic sense. Thom Stu wrote: > > > Was Darwin's statement "It has been experimentally pro

Re: An Interesting Student Problem

> Was Darwin's statement "It has been experimentally proved that if a plot of > ground be sown with one species of grass, and a similar plot be sown with > several distinct genera of grasses, a greater number of plants and a greater > weight of dry herbage can be raised", a valid statement? I emp

Re: »¹ÊǺÍÒÔÇ°Ò»ÑùÂ𣿠£º£©

<[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > 2001ÄêÍøÂçƱѡ½Ü³öMLMÕ¾µã£¬Îñ±ØÒªÄÍÐÄä¯ÀÀŶ£º > > http://www.kelvin.13800.com > ÐÂÓ¯ÀûÉÌÎñÐÅÏ¢ÍøÂç > http://www.kelvin.uurr.com > ´ó¼Ò׬ÉÌÎñÐÅÏ¢ÍøÂç > http://www.kelvin.17951.com > ½ðӯͨÉÌÎñÐÅÏ¢ÍøÂç > http://www.

RE: Interpreting multiple regression Beta is only way?

-Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Wuzzy Sent: Monday, February 04, 2002 4:14 PM To: [EMAIL PROTECTED] Subject: Re: Interpreting mutliple regression Beta is only way? ... I've heard of "ridge regression" will try

Re: Method for determining gaussian distribution

Jennifer Golbeck wrote: > > i hope someone can help me with this. i have finished a computer science > study that examines swarming behavior. my claim is that the swarming > algorithm that i use produces a gaussian distribution - on a grid, the > frequency that each area is visited is recorded. g

Re: Interpreting mutliple regression Beta is only way?

> > In biostatistical studies, either version of beta is pretty worthless. > Generally speaking. If I may be permitted to infer a reason: if you have bodyweight= -a(drug) - b(exercise) + food Then the standardized coefficients will affect bodyweight but they will also affect each other. The

Re: Log-rank & Mantel-Haenszel

"R. Stegers" <[EMAIL PROTECTED]> wrote in message news:... > I'm trying to understand some medical paper and they used both Log-rank and > Mantel-Haenszel. Could anybody briefly explain what is measured by these > specific tests? Why are they used (in general) en what

Re: Log-rank & Mantel-Haenszel

"R. Stegers" <[EMAIL PROTECTED]> wrote in message news:... > I'm trying to understand some medical paper and they used both Log-rank and > Mantel-Haenszel. Could anybody briefly explain what is measured by these > specific tests? Why are they used (in general) en what

Re: how to adjust for variables

Wuzzy wrote: > > > Walter Willett has a whole chapter on this subject in his book Nutritional > > Epidemiology. It should be considered required reading before attempting to > > model anything that has to do with diet. > > Thanks this is a really good book, not just for ppl wanting to study > n

Re: Definition of "Relationship Between Variables" (was Re: Eight

Or maybe I didn't understand Don's response to Jan. Pressing ever onward, though I had suggested using > DEFINITION: There is a *relationship* between the vari- > ables x and y if for at least one pair of values x' > and x" of x > > E(y|x') ~= E(y|x").

Re: The exam questlons will probably be tougher

On 3 Feb 2002 03:34:35 -0800, [EMAIL PROTECTED] wrote: [ snip, previous examples ... ] > > Asked about statistics practice problems. Search took 0.35 seconds > Got about 945,000. hits. > > Nuff said, - Right idea, sloppy technique; I would say in my critique. Google hits 966,000 for me,

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